If so, would both borrower and lender be charged the same or just one party?  

Sorry to be a little late to the party, but I am not clear on what exactly you want to do.Do you want to separate the first floor from the basement and then use the basement for a crash pad for when you visit?

You could determine FMV for property management and compensate the party providing it even if it's one of you. 

From the hosting side it is a 20 min turnover and there are no parties with just 2 guests. 

Hi Hannah, I hate to be a party pooper but you won't get any construction loan or any other type of loan in Mexico to finance the construction of a house there.If you don't have cash, your only options would be to borrow in the US.

How about using 3rd party management? 

Invasion of privacy, unclean and rude house members, maybe if they do drugs or smoke or are party animals, unwanted friends of theirs visiting at odd hours, clashes of personality

HI @Dan Ashley,I agree that partnering with someone would be beneficial for both parties.

A lease can spell out rules and expectations and its more than just a contract its a way to COMMUNICATE between parties.

Both parties are deceased with no known heirs and unfortunately, we do not have the necessary information to get a copy of the death certificates.